The invention concerns an automatic clutch in the drive train of a motor vehicle, having a transmission which can be manually or arbitrarily shifted between gears or drive positions with different transmission ratios and passes through a neutral or idling position during a gear change or change of drive position. A motorized adjusting unit, which is controlled by a system of sensors, actuates the clutch and releases the clutch when the system of sensors detects that the respectively previously selected drive position or the previously selected gear is being left.
Vehicles with customary internal combustion engines require a drive train with a transmission in order to be able to adapt the transmission ratio between the engine speed and the speed of the drive wheels of the vehicle to different conditions. In the case of customary manually shifted transmissions, the shifting element or the shift lever in each case passes through a neutral or idling region when changing gears or drive positions.
During the changing of gears or drive positions in the case of customary transmissions the clutch must be released.
In addition to clutches operated by the driver by use of a pedal or the like, automatically actuated clutches are also known in principle and used as standard.
U.S. Pat. No. 5,377,797 shows, by way of example, a clutch of the above-mentioned type. The clutch is engaged and released when the shift lever of the transmission sufficiently approaches a position assigned to a drive position and, respectively, is moved sufficiently away from this position.
Moreover, in the case of automatic clutches there is also a desire for a system of sensors which senses various parameters. In particular, the system of sensors can register which drive position or which gear has been selected. This is important and advantageous because the clutch is to be released as quickly as possible when shifting is intended by the driver, i.e. whenever a previously selected gear or a previously selected drive position is being left, in order to avoid major wear to the clutch and/or damage to the transmission.
It has already been attempted to use the signals for the respectively selected gear or the respectively selected drive position sensed by the system of sensors also for controlling a gear or drive-position indication.
German Patent document DE-U 89 13 910 concerns a drive-position indication.
The object of the invention is thus to present advantageous arrangements for automatic clutches.
This object is achieved according to the invention by providing an indication for the respectively selected gear or the respectively selected transmission stage as well as the neutral or idling position. According to the invention, it is possible to suppress the indication for the neutral or idling position during a change of gears or drive positions.
The invention is based on the general idea of not indicating the passing through of the neutral or idling position as long as the intention of the driver to carry out a change of gears or drive positions is evident or very probable on the basis of the parameters sensed by the system of sensors. This offers the advantage that the driver cannot be irritated when changing gears or drive positions by indicating signals which merely are assigned to a state of the transmission necessarily passed through in a temporary fashion, that are of no significance for the shifting intended by the driver and that are not desired by the driver as a final state.
According to a preferred embodiment of the invention, it may be envisaged to make the indication of the neutral or idling state possible only after a delay time, the length of which is set to correspond to the typical time interval of a gear change or change of drive position. This makes it possible in a way which is simple in design terms--for example by a delay circuit--that during a customary gear change or change of drive position the neutral or idling state necessarily passed through during such a change is not indicated. On the other hand, an indication of this state remains possible whenever the driver actually selects the idling or neutral state.
According to a further particularly preferred embodiment, it may be envisaged to sense the speed of movement with which the driver actuates the corresponding control element, generally a shift lever, during the gear change or change of drive position.
The sensing of this parameter is provided in an advantageous way for controlling the clutch. This is because the speed of movement is an indication of whether the driver prefers a more sporty style of driving or a style of driving based more on comfort, since sporty drivers will generally carry out the gear change or change of drive position very rapidly, while this change takes place comparatively slowly if the greatest possible driving comfort is desired. Consequently, when sensing the speed of the gear change or change of drive position, control of the clutch can also be adapted to the respective driving style, in that the slipping phase during engagement of the clutch is shortened, for example, in the case of a sporty driving style and is lengthened in the case of a driving style conscious of comfort.
Thus, according to the invention the signal for the speed of movement of the control element or shift lever of the transmission can also be utilized in the suppression or execution of the indication of the idling or neutral state. If the idling or neutral state is passed through at a certain minimum speed, this represents a reliable indication of the intention of the driver to change the gears or drive positions. In this case, the indication of the neutral or idling state does not occur. With a diminishing speed of the movement of the control element or shift lever of the transmission in the region of the idling or neutral position, on the other hand, it must be expected that the driver actually intends to select the neutral or idling state. In this case, this state is immediately indicated.
Otherwise, with regard to preferred features of the invention, reference is made to the claims and the following explanation of the drawing, on the basis of which particularly advantageous embodiments are described.